Subject: Why are kids taught that a rainbow has 7 colours?

What I’d like to know is where did Sir Isaac get Indigo from?

Like every other kid in the street, I was brought up to react to the 
question “What are the colours of the rainbow?” with Roy G Biv  -that’s red, 
orange, yellow, green, blue, indigo, violet.

Now, old Isaac must have known that the spectrum of light comprised an 
infinite range of colours –after all he had an IQ that was off the Richter 
scale-but he decided that the peasants would like to see bands of colours that 
they could name to their little ones. Very good, but unless you’re going to 
include white, why on earth pick seven?  And why indigo?

I mean, if I make myself a colour wheel like the Art teacher used to insist 
on, I start with the three (painting) primaries -red, yellow and blue; next 
the secondaries -orange, green and purple; then the tertiaries –vermillion, 
amber (or orange-yellow), lime (or Chartreuse), turquoise (or acquamarine), 
violet, and magenta.
I’ve now got twelve and there’s still no sign of Indigo, which would sit 
between the blue and the violet.

Could it be he had a mistress who wore indigo underwear?

Re: Why are kids taught that a rainbow has 7 colours?